1. Field of the Invention
The present invention relates to an inductive magnetic head used in, for example, a floating magnetic head, and more particularly, to a method of manufacturing a magnetic head in which a track width of a recording magnetic gap is precisely formed and light fringing can be suppressed.
2. Description of the Related Art
FIG. 15 is a partial front view of the vicinity of a magnetic pole of a conventional magnetic head, which is viewed from the surface opposing a recording medium, and FIG. 16 is a partial longitudinal cross-sectional view of the magnetic head shown in FIG. 15. The magnetic head shown in FIGS. 15 and 16 is an inductive head for writing a signal onto the recording medium such as a hard disk. This inductive head is laminated on a reading head using a magnetoresistance effect in the trailing side section of a slider of the floating magnetic head opposing to the recording medium such as a hard disk. However, the magnetic head may be composed of only the inductive head, without providing the reading head.
Reference numeral 201 shown in FIGS. 15 and 16 denotes a lower core layer formed of a magnetic material having a high magnetic permeability, such as Fe—Ni based alloy (Permalloy). A compound type thin film magnetic head on which the inductive head shown in FIGS. 15 and 16 is successively laminated at upper side (Z direction) of the reading head (not shown) using the magnetoresistance effect is composed and the lower core layer 201 functions as an upper shielding layer of the reading head. The lower core layer 201 is formed with a rectangular protrusion 201a integral with the lower core layer 201.
On the lower core layer 201, a gap layer 203 made of non-magnetic material such as Al2O3 (alumina) is formed. On the gap layer 203, a coil insulating underlaying layer 204 made of resist material or other organic material is formed.
On the coil insulating underlaying layer 204, a coil layer 205 made of a conductive material having a low electric resistance, such as Cu, is formed in a spiral shape. Further, the coil layer 205 is formed so as to surround the periphery of a base end 207b of an upper core layer 207, but only a portion of the coil layer 205 is shown in FIG. 16.
Therefore, on the coil layer 205, an insulating layer 206 composed of an organic insulating material or an inorganic insulating material is formed. On the insulating layer 206, a magnetic material having a high magnetic permeability, such as Permalloy, is plated to form the upper core layer 207. The front end 207a of the upper core layer 207 is bonded onto the lower core layer 201 through the gap layer 203 in the portion opposing the recording medium and a magnetic gap having a gap length G1 is formed. Further, the base end 207b of the upper core layer 207 is magnetically connected to the lower core layer 201.
In the writing inductive head, if a recording current is applied to the coil layer 205, a recording magnetic field is induced to the lower core layer 201 and the upper core layer 207 and the magnetic signal is recorded in the recording medium such as the hard disk by a leakage magnetic filed from the magnetic gap between the lower core layer 201 and the front end 207a of the upper core layer 207.
Furthermore, on the top surface of the lower core layer 201 extending in the both sides of the base end of the protrusion, slopes 201b, 201b are formed.
In the magnetic head shown in FIGS. 15 and 16, since the protrusion 201a is formed, the leakage magnetic field generated between the protrusion 201a and the upper core layer 207 is surely converged in the width Tw (=track width) of the upper core layer 207 and thus the light fringing can be suppressed. Also, since the slope 201b is formed at the lower core layer 201 and the distance between the slope 201b and the upper core layer 207 can be widened, it is difficult to generate the leakage magnetic field between the upper core layer 207 and the lower core layer 201 extending from the base end of the protrusion 201a and thus the light fringing can be suppressed.
The method of manufacturing the inductive head is disclosed in Japanese Unexamined Patent Application Publication No. 2001-143222 (hereinafter, refer to Patent Document 1). FIGS. 17 and 18 show a process for forming a magnetic pole of the inductive head described in paragraph [0135] of Patent Document 1.
In the method of manufacturing the magnetic pole of the inductive head described in Patent Document 1, as shown in FIG. 17, the gap layer 203 and the front end 207a of the upper core layer 207 are formed in this order from the lower side, on the lower core layer 201 of which the front shape which is viewed from the surface opposing the recording medium is rectangular. At this time, the states of the gap layer 203 and the front end 207a of the upper core layer 207 are shown by a dashed line and the width in the track width direction (X1-X2 direction) of the gap layer 203 and the front end 207a is T5.
Next, for example, the sides of the gap layer 203 and the front end 207a are cut by an ion milling process in which an ion irradiating angle θ10 is in the range of 60° to 75° and the width in the track width direction of the gap layer 203 and the front end 207a is T6. The width T6 is controlled to the track width Tw. The states of gap layer 203 and the front end 207a at this time are shown by a solid line in the drawing. Also, the top surface 201c of the lower core layer 201 is cut from the state shown by the solid line to the state shown by the dotted line and thus the protrusion 201a is formed on the lower core layer 201.
Next, as shown in FIG. 18, if the ion irradiating angle θ11 is changed in the range of 45° to 60° to form the slope 201b at the top surface 201c of the lower core layer 201, and the magnetic pole of the conventional inductive head shown in FIGS. 15 and 16 is formed.
On the other hand, FIGS. 3A through 3E of U.S. 005867890A (hereinafter, refer to Patent Document 2) describes another method of forming the magnetic pole of the inductive head. In the process shown in FIG. 3A of Patent Document 2, a gap layer (G) is entirely formed on a bottom pole piece (P1/S2) which functions as the lower core layer and a top pole piece (PT2) which functions as the upper core layer is formed on the gap layer. Next, after forming a non-magnetic material layer (SL) from the top pole piece (PT2) to the gap layer (G) in the process shown in FIG. 3B, the non-magnetic material layer (SL) and the gap layer (G) formed on the top surface of the bottom pole piece (P1) is removed by using a reactive ion etching (RIE) method in the process shown in FIG. 3C, and then the non-magnetic material layer (SL) is formed at the side of the top pole piece (PT2) as shown in FIG. 3D. At this time, the width of the non-magnetic material layer (SL) is a constant width in the vertical direction. Next, as shown in FIG. 3E, the bottom pole piece (P1/S2) is cut by the ion milling process and a bottom pole chip element (PT1a) and a top pole chip element (TP1b) which is the protrusion are formed in the bottom pole piece (P1/P2), thereby forming the magnetic pole of the inductive head.
However, in the method of manufacturing the inductive head shown in FIGS. 17 and 18 of Patent Document 1, when the top surface 201c of the lower core layer 201 is cut to form the slope 201b in the process shown in FIG. 18, the cut lower core layer 201 is reattached to the front end 207a of the upper core layer 207 and the gap layer 203 and thus a reattached layer 201d is formed at the side of the front end 207a of the upper core layer 207 and the side of the gap layer 203.
Here, since both the lower core layer 201 and the upper core layer 207 are formed of the magnetic material such as Permalloy, there is a problem in that the track width Tw controlled in the process shown in FIG. 18 becomes substantially large.
On the other hand, in the method of manufacturing the inductive head described in Patent Document 2, the top pole chip element (PT1b) is formed by forming the non-magnetic material layer (SL) at only the side of the top pole piece (PT2) and then cutting the bottom pole piece (P1/S2) at an interval controlled by the width between one outside and the other outside of the non-magnetic material layer (SL) formed with a constant width in the vertical direction. Since the width of the top pole chip element (PT1b) cut by the ion milling process is the width between one outside and the other outside of the non-magnetic material layer (SL), the width of the top pole piece (PT2) is different from that of the top pole chip element (PT1b) at the boundary of the gap layer (G). Accordingly, when the recording magnetic filed generated from the top pole piece (PT2) formed with a narrow width flows through the bottom pole piece (P1/S2) formed with a wide width, the recording magnetic field becomes spread and the light fringing is apt to be generated.
Further, when cutting the bottom pole piece (P1/S2) by the ion milling process in the process shown in FIG. 3E, the non-magnetic material layer (SL) is formed at the side of the top pole piece (PT2). Therefore, the width of the top pole piece (PT2) is not reduced by the ion milling process. However, since the non-magnetic material layer (SL) is not formed at the side of the gap layer (G), the side of the gap layer (S) is cut or the bottom pole piece (P1/S2) cut by the ion milling process is reattached to the side of the gap layer (G) upon the ion milling process and thus the width of the gap layer (G) is varied.